Collaborative Research: Connecting the Past, Present, and Future Climate of the Lake Victoria Basin using High-Resolution Coupled Modeling

合作研究：使用高分辨率耦合建模连接维多利亚湖盆地的过去、现在和未来气候

• 批准号: 2323649
• 负责人: Daniel Peppe
• 金额: $ 13.75万
• 依托单位: Baylor University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2024
• 资助国家: 美国
• 起止时间: 2024-03-01 至 2027-02-28
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2323649&HistoricalAwards=false
• 关键词: Collaborative; Research; Connecting; Past; Present

Lake Victoria, the largest lake in Africa and the second largest in the world, is big enough to make its own weather. The lake's influence on weather is evident in rainfall totals, as considerably more rain falls over the lake than the catchment around it, and in the diurnal cycle of rainfall, as the lake creates a land-sea breeze effect which causes rain to fall during the day over the land and at night over the lake. Given the lake's outsized influence on weather it is natural to ask what role it will play in climate change over the Lake Victoria Basin. The question of Victoria's role in climate change is challenging for several reasons, among them the lack of observations over the region and the difficulty of making simulations which capture the range of scales and processes that matter for the region's weather and climate. Regarding the spatial scales the range extends from the size of the mesoscale thunderstorm complexes the deliver much of the rain to the regional-scale circulation patterns that control the seasonality of rainfall. The region could also be influenced by changes in surface temperature over the Indian and Atlantic Oceans.Research conducted here takes up the challenge of Victoria Basin climate change using a nested modeling strategy in which a regional model, the Weather Research and Forecasting (WRF) model, is run with three nested grids to capture the relevant scale range. The outer grid covers all of Africa and much of the Atlantic and Indian Oceans with a 27km grid spacing while the innermost grid covers the Lake Victoria Basin at 3km, sufficient resolution to capture thunderstorm complexes. WRF is coupled to the Community Land Model (CLM), which includes a representation of Lake Victoria and its interactions with the overlying atmosphere.The work involves simulations of past, present, and projected future climate over the basin. Past climate simulations focus on a period 17 thousand years ago when the lake dried out completely, and the PIs hypothesize that the dessication of the lake was the result of changes in incoming solar radiation due to Earth's orbital cycle (which also caused the ice ages). The project also considers the more general question of how regional climate depends on the size of Lake Victoria, which can be varied in the model simulations. Changes in lake size could drive precipitation changes that cause further lake size change, as the lake receives perhaps 80% of its water input from local rainfall (rivers flowing into the lake provide the other 20%).The work is of societal as well as scientific interest given that about 40 million people live in the Lake Victoria Basin and are dependent on its water resources. Rainfall is a hazard as well as a resource given that much of the rain falls in severe storms, a particular hazard for the fishing fleet. The PIs conduct public outreach regarding climate change in the region through a traveling museum exhibit to be presented at the Mayborn Museum at Baylor University and at the National Museum of Kenya. In addition, the project provides support and training to two graduate students at the University of Texas at Austin and one at Baylor University.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

维多利亚湖是非洲第一大湖、世界第二大湖，其面积足以创造自己的天气。 湖泊对天气的影响在降雨总量中表现得很明显，因为湖泊上的降雨量比其周围集水区的降雨量要多得多，而且在降雨的昼夜周期中，湖泊产生的陆海风效应导致降雨在白天在陆地上，晚上在湖上。 鉴于该湖对天气的巨大影响，人们很自然地会问它将在维多利亚湖盆地的气候变化中发挥什么作用。 维多利亚州在气候变化中的作用问题具有挑战性，原因有几个，其中包括缺乏对该地区的观测，以及难以进行模拟来捕捉对该地区天气和气候至关重要的规模和过程的范围。就空间尺度而言，范围从中尺度雷暴复合体的大小延伸到控制降雨季节性的区域尺度环流模式。 该地区还可能受到印度洋和大西洋表面温度变化的影响。这里进行的研究利用嵌套建模策略应对维多利亚盆地气候变化的挑战，其中区域模型、天气研究和预报 (WRF) 模型，使用三个嵌套网格运行以捕获相关的比例范围。 外部网格覆盖整个非洲以及大西洋和印度洋的大部分地区，网格间距为 27 公里，而最内部网格覆盖维多利亚湖盆地，网格间距为 3 公里，分辨率足以捕获雷暴复合体。 WRF 与社区土地模型 (CLM) 相结合，其中包括维多利亚湖的表示及其与上覆大气的相互作用。这项工作涉及对该盆地过去、现在和预测的未来气候的模拟。 过去的气候模拟集中在 17000 年前，当时湖泊完全干涸，PI 假设湖泊干涸是由于地球轨道周期（这也导致了冰河时代）引起的入射太阳辐射变化的结果。 该项目还考虑了一个更普遍的问题，即区域气候如何取决于维多利亚湖的大小，而维多利亚湖的大小在模型模拟中可能会有所不同。 湖泊规模的变化可能会推动降水量的变化，从而导致湖泊规模的进一步变化，因为湖泊的水输入量大约有 80% 来自当地降雨（流入湖泊的河流提供了另外 20%）。 这项工作既涉及社会又涉及社会鉴于大约 4000 万人生活在维多利亚湖盆地并依赖其水资源，因此具有科学兴趣。 降雨既是一种危险，也是一种资源，因为大部分降雨都发生在严重的暴风雨中，这对捕鱼船队来说尤其危险。 PI 通过在贝勒大学梅伯恩博物馆和肯尼亚国家博物馆举办的巡回博物馆展览，对该地区的气候变化进行公众宣传。 此外，该项目还为德克萨斯大学奥斯汀分校的两名研究生和贝勒大学的一名研究生提供支持和培训。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查进行评估，认为值得支持标准。